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Brightwater Treatment Plant

Find information and facts about Brightwater Treatment Plant located near Woodinville, including the treatment process, capital and improvement projects, and visiting the facility and grounds.

January 2024

King County is replacing Brightwater Treatment Plant’s state-of-the-art filtration system for the first time since 2011. The membranes filter out particles as small as viruses and bacteria from wastewater before the clean water is piped to Puget Sound. Stacked end to end, the 17 million membranes would stretch around the entire Earth! Read how operators are replacing the membranes in King County’s Clean Water Stories.

Visit Brightwater’s Public Engagement web page to read past emails, newsletters, and blog stories related to Brightwater. Sign up for our emails to stay up to date!


Located just north of Woodinville, Brightwater Treatment Plant (Brightwater) began operating in 2011. It is our newest regional wastewater treatment facility and features an educational and event center, natural areas and hiking trails, and public art. Brightwater treats an average of 36 million gallons of wastewater per day from communities in northeast King County and southeast Snohomish County. The facility is nationally recognized for its award-winning design and its consistent compliance with state and federal discharge limits.


Aerial view of the Brightwater treatment plant, looking north.  

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